ABSTRACT Childhood cancer is the leading cause of child death by disease past infancy in the US. While survival has improved, mainly due to patient participation in clinical trials, critical racial/ethnic disparities remain. Compared to non-Hispanic White (NHW) children, Hispanics have higher incidence of leukemia and poorer survival rates. Although Hispanics will comprise 33% of the U.S. childhood population by 2060, their participation in biomedical research is critically low and, as shown in our prior work, Hispanics are underrepresented in pediatric cancer research. As a result, outcomes data are obtained mostly from NHW. Our preliminary data, and research from others, suggest that adequate informed consent and low research literacy (capacity to understand and act on information to make decisions about research) are barriers to minority participation in clinical trials. Interventions to improve research literacy and clinical trial participation, particularly for Hispanics, are lacking. There is an urgent need to fill this gap in knowledge, as tailored interventions guided by implementation science can improve research literacy and minority participation in clinical trials. The objective of this K08 is to improve research literacy in parents of children with leukemia by adapting (from the patient- navigation model) and implementing ?COMPRENDO? (ChildhOod Malignancy Peer REsearch NavigatiOn), a tailored peer-navigation intervention (PNI). Our hypothesis and rationale are that PNIs guided by implementation science, in which trained peers deliver culturally and linguistically concordant education to parents during informed consent, can identify and address barriers to: a) adequate research literacy, and b) equitable clinical trial participation. By increasing minority participation in clinical trials, we can effectively translate discoveries and treatments, and, ultimately, improve equity of survival in diverse populations, which is a top priority for NCI. We propose to implement COMPRENDO to improve parental research literacy in pediatric leukemia clinical trials, using mixed-methods and implementation science (Aim 1). We will compare the effectiveness of COMPRENDO vs. usual care in improving research literacy outcomes among parents of children with leukemia (Aim 2) using a Hybrid Trial Type 1 effectiveness and implementation design. We hypothesize that, compared to usual care, parents randomized to the PNI will show higher comprehension, voluntariness, and accrual and lower mistrust post informed consent discussion and 4 weeks post intervention. This K08 award builds on the formative work of the PI in bioethics and pediatric cancer disparities and maps on to the PI?s training goals in implementation science, intervention adaptation, qualitative methods, and behavioral clinical trial design. This K08 has an important impact: knowledge gained can be generalized to Hispanics across the lifespan and will help to: a) inform clinical care, and b) design a multi-site randomized clinical trial, in which COMPRENDO will be tested in a larger sample of Hispanics with a broader range of cancers in a future R01, enabling the PI?s transition to independence as a successful physician-scientist.